Compatible Coils for Use with HotSpark® Ignition
Applies to Hot-Spark 3-Series (red) ignition kits
Coil Warning: DO NOT use a low-resistance or an HEI-style coil. Use a coil that has resistance in the primary circuit of at least 3.0 Ohms (Ω). Using a coil with insufficient primary resistance can cause the ignition module to overheat and misfire until it cools down again, or fail prematurely, which will void the Hot-Spark ignition warranty.
14.0 Volts Maximum Charging System Voltage: Charging system voltage, measured at the coil's + terminal, must never exceed 14.0 volts at any RPM level. To lessen the impact of over-voltage and voltage surges to the ignition module, a 1.4 Ohm ballast resistor can be wired between the coil's + terminal and the RED HotSpark ignition wire. Otherwise, too much voltage/amperage can damage the ignition module.
DO NOT reverse the polarity of the RED and BLACK wires - it will destroy the ignition module (and void its warranty)! The Hot-Spark module’s red wire connects to positive ( + or 15 on Bosch coil). The black wire connects to negative ( - or 1 on Bosch coil). Remove the condenser and its wire from vehicle. All other wires are connected to the coil in their original places. This module is designed for 12V negative ground applications only.
Make sure that the ignition wires have plenty of slack inside the distributor and are not rubbing on any moving parts. If you need to extend the length of the ignition wires, use 18- or 20-gauge (AWG) wire. Crimp tightly or solder (best) and insulate all connections.
The BERU Germany Blue Coil has 3.3 Ω primary resistance. Ideal for use with HotSpark ignition kits.
The following 12-volt Bosch® coils should be compatible with the Hot-Spark electronic ignition module (4-cylinder):
0 221 119 021 (Bosch Black coil)
0 221 119 020 (Bosch Black coil) (VW 022 905 115C)
0 221 119 027 (Bosch Blue coil) (VW 043 905 115C)
9 220 081 039 (Brazil)
9 220 081 054 (Brazil)
9 220 081 083 (00 012) (Bosch Blue coil)
0 439 051 15C (00012) (Bosch Silver Coil)
The Bosch coils above should have a primary winding with 3.0 to 3.3 Ω resistance. Bosch coils are made in a number of countries, with varying amounts of primary and secondary resistance. It's best to check the coil's primary resistance with an Ohmmeter (a digital multi meter in the 200 Ω mode). Install a 1.4 Ω or so external ballast resistor (HS14BR) between the ignition switch (+12-Volt power source) and the coil's + terminal, if the coil's primary resistance is questionable or borderline.
Bosch 0 221 119 030 (Bosch Red Coil, Brazil) 1.6 Ω to 1.8 Ω primary resistance (OK for 6- or 8-cylinder ignition kits, not enough primary resistance for 4-cylinder ignition kits).
BERU Germany Blue Coil: 3.3 Ω primary resistance
Lucas® Coil Primary Resistance:
DLB105 3.0 Ω (oil-filled)
DLB101 3.0 Ω (oil-filled)
Flame-Thrower® (made in China) Coil Primary Resistance:
40501 3.0 Ω (oil-filled)
40511 3.0 Ω (oil-filled)
40611 3.0 Ω (epoxy-filled)
Do not use any other Flame-Thrower®
coil, as it won't have enough primary resistance, allowing too much amperage to
flow to the ignition module, destroying the module or shortening its life.
Duralast® (Autozone) LU800 3.3 Ω primary resistance, 8.3K Ω secondary resistance
Wells® LU800 3.3 Ω primary resistance, 8.3K Ω secondary resistance (oil-filled)
Import Direct 23-0254 3.2 Ω primary resistance, secondary resistance: 7.8K Ω
Measuring Coil Primary Resistance: Coil must have a minimum of 3.0 Ohms primary resistance. To measure primary resistance: Label and remove all wires to coil ( + or - ). Using a common digital multimeter in the 200 Ω mode, cross the red and black leads of the Ohmmeter. Allow a few seconds for the reading to settle and write down the reading.
Still in the 200 Ohm mode, measure between coil’s + and - terminals. Allow a few seconds for the reading to settle, until it stabilizes. Subtract the previous reading, taken with the leads crossed, to compensate for multimeter’s inherent resistance. Do not use a low-resistance coil, such as the MSD or Accel coil; they don’t have enough primary resistance for this application. Using a coil with too little primary resistance can cause the ignition module to overheat and misfire until it cools down again or fails, voiding the warranty.
Coil Secondary Resistance: For
best performance, coil should have 7K Ohms or more secondary resistance. To measure
secondary resistance: Label and remove all wires to coil ( + or - ). Using a
common digital multimeter in the 20K Ω mode, place one Ohmmeter lead on the
coil's + or - terminal and the other Ohmmeter lead in the coil's center
high-tension wire socket, the socket that holds the lead from the center of the
coil to the center of distributor cap.
Check the voltage reading at the coil's + terminal, engine running, at maximum RPM at the coil's positive terminal. If the voltage reading is more than 14.0 volts at any RPM level, the voltage regulator likely needs replacing or a 1.4 Ohm ballast resistor should be wired between the coil's + terminal and the red HotSpark ignition wire. Too much voltage can damage the ignition module and other electronic components. The ballast resistor is usually mounted on the firewall or directly on the coil.
If the charging system voltage, measured at the coil's positive terminal, is more than 14.0 volts at any RPM level, the voltage regulator likely needs replacing or a 1.4 Ohm ballast resistor should be wired between the coil's + terminal and the red HotSpark ignition wire. Too much voltage can damage the ignition module and other electronic components. Charging system voltage of 13.6 volts or so is plenty.
Ohmmeter Calibration: When the Ohmmeter’s red and black leads are connected to each other, the reading should be 0.00 or very close to zero. If, though, for example, with both Ohmmeter leads shorted together, the reading is 0.5 Ω, you’ll need to subtract 0.5 Ω from the reading you get when measuring the coil’s primary resistance. For example, if the coil’s primary resistance reading is 3.5 Ω, but when the Ohmmeter leads are shorted together the reading is 0.5 Ω, then the coil’s primary resistance is 3.0 Ω: 3.5 Ω - 0.5 Ω = 3.0 Ω. This calibration procedure applies only to resistance measurements made in the 200 Ω mode of a digital Ohmmeter.
The inherent resistance of the leads is negligible in higher Ω modes of the Ohmmeter. If you’re using an analog Ohmmeter, touch the leads together while setting the needle on zero before measuring resistance.
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